The present invention generally relates to content delivery systems. More specifically, the present invention relates to a method and system for optimizing use of channel bandwidth in on-demand systems.
Traditional digital cable, satellite and terrestrial broadcast systems include many frequency division multiplexed radio frequency (RF) channels. Typical on-demand services, such as video-on-demand and stream media through cable network or satellite systems, are often limited by the hard frequency limitations, as shown in FIG. 1, where each subscriber is tuned to a certain frequency band to receive the desired content. For a true on-demand system, very often, there are multiple copies of the same content flowing through the network with slight time differences. As shown in FIG. 1, at beginning of the service, a subscriber sends in a request for a desired service. In response, the network allocates part of one RF channel for the service requested. If there are multiple users requesting the same content at different times, then very often, there are multiple copies of the same content being delivered on different RF channels at the same time.
FIG. 2 is a simplified schematic diagram illustrating delivery of content streams in a conventional video-on-demand system. Referring to FIG. 2, a typical video-on-demand system includes a network center that controls delivery of audio/video (A/V) content streams to subscribers. A subscriber can be located in one of many possible locations, such as, a home or residence. Each subscriber location is connected to the network center via a communication channel. In a standard video-on-demand system, each subscriber needs one content stream, which is limited with one RF channel. Each RF channel, however, is able to support multiple content streams. When a particular program is requested by a first subscriber, the network center causes an A/V content stream representing the requested program to be sent to the first subscriber's location via a corresponding RF channel. When the same program is requested by a second subscriber at a later time, the network center again causes a second A/V content stream representing the same requested program to be sent to the second subscriber's location via a corresponding RF channel.
The foregoing typical video-on-demand system suffers from content stream redundancy. When the same program is requested by different subscribers at different times, various RF channels are then needed to carry the same A/V content streams (the only difference between two content streams being that they are time-shifted versions) which results in inefficient use of the communication channel bandwidth. This inefficiency becomes further exacerbated as more and more A/V content streams representing the same content need to be delivered. As a result, an increasingly higher percentage of the total available bandwidth within all the RF channels is utilized to carry the same content.
Furthermore, in a traditional system, contents for a single program are delivered via a single corresponding channel. Therefore, each on-demand subscriber is only able to view one on-demand channel at a time, even if there is excess capacity available in other RF channels. Consequently, excess capacity that is available in other RF channels cannot be utilized by the on-demand subscriber.
Hence, it would be desirable to provide a method and system that is capable of optimizing channel bandwidth in a content delivery system.